High count transmission media plenum cables which include non-halogenated plastic materials

Abstract

A cable which may be used in buildings in concealed areas such as in plenums or in riser shafts includes a core (22) which in a metallic conductor cable includes at least twenty-five transmission media each of which is enclosed with a non-halogenated plastic material. The core is enclosed with a jacket (28) which also is made of a non-halogenated plastic material. The non-halogenated plastic material of the insulation is selected from the group consisting of a polyetherimide and a silicone-polyimide copolymer, or a blend comprising the polyetherimide and the silicone-polyimide copolymer. For the jacket, the plastic material includes a blend composition of silicone-polyimide copolymer and a flame retardant and smoke suppressant system comprising titanium dioxide and zinc borate.

We claim: 
     
       1. A communications cable, which is suitable for building plenum use, said cable comprising: a core which comprises a relatively large number of communications transmission media, each communications transmission medium being enclosed with a plastic material which is selected from the group consisting of a polyetherimide, a silicone-polyimide copolymer, and compositions which include a polyetherimide and a silicone-polyimide copolymer; and   a jacket which encloses said core and which comprises a plastic material comprising a silicone-polyimide copolymer and a system comprising a composition which includes titanium dioxide and zinc borate that enhances the flame retardancy and smoke suppression characteristics of said cable sufficiently to protect a relatively large number of transmission media.   
     
     
       2. The cable of claim 1, wherein said jacket is a composition which comprises as much as 20% by weight of said composition of titanium dioxide and zinc borate. 
     
     
       3. The cable of claim 2, wherein said titanium dioxide and said zinc borate each is included in the amount of about 0.5 to 15% by weight of said composition. 
     
     
       4. The cable of claim 1, wherein said blend composition comprises 1% by weight of titanium dioxide and 1% by weight of zinc borate. 
     
     
       5. The cable of claim 1, wherein said jacket is a composition which comprises a polyetherimide and a silicone-polyimide copolymer and as much as about 20% by weight of said composition of titanium oxide and zinc borate. 
     
     
       6. The cable of claim 1, which also includes a core wrap which is disposed between said core and said jacket. 
     
     
       7. The cable of claim 1, which also includes a metallic shield, said metallic shield being disposed between said core and said jacket. 
     
     
       8. The cable of claim 1, wherein each transmission medium in said core comprises an optical fiber and said plastic material which encloses said optical fiber is a buffer layer comprising a silicone-polyimide copolymer.